【正文】 age)Evaporating/condensing temperaturesTemperatures of water/antifreeze solution at ground heatexchanger inlet/outletVolumetric flow rates of air/water/antifreeze solutionSoil temperature in depth of 2 mOutdoor air temperatureTemperatures of air at the condenser fan inlet/outletPower input to the pressorPower input to the brine circulating pump/the condenser fanTotal power input to the whole systemHeat extraction rate from the groundHeating load of the room testedHeat extraction rate per meter of horizontal groundheat exchanger lengthHorizontal ground heat exchanger length in m per kW of heatingHeating coefficient of performance of the heat pump unitand whole systemaSome thermodynamic data were taken from [4,13].C03m3/s15 8C0 8C kW kW kW kW kW/m m/kW–C015/42 8CValue UnitC15Pump:˙Exdest。v=v0222。C138254。1254。1:6078v0222。240。1:6078v222。RaT0f240。P=P0222。1:6078v222。240。T=T0222。T=T0222。T0189。vCp。Cp。 (15)The total flow exergy of air is calculated from [14]:ca188。C0T0240。240。˙QrC181 C0T0TgroundC19(21)O. Ozgener, A. Hepbasli/Energy and Buildings 39 (2020) 66–7570Table 2Benchmarksforgroundcoupledheatpumpsystempumpingefficiencyrequiredpump power to cooling capacity and a parison of the ground source heatpump system I studiedWatts input Performanceper tonne per kW Efficiency GradeBenchmarks for groundcoupled heat pump system [17,18]50 or less 14 or less Efficient systems A: excellent50–75 14–21 Acceptable systems B: good75–100 21–28 C: mediate100–150 28–42 Inefficient systems D: poorGreater than 150 Greater than 42 E: badThe value obtained from the ground source heat pump system I studied Efficient systems Excellentcalculated by:cr。cinC0 cout222。grh188。X˙ExinC0X˙Exout188。 T0˙Sgen(19)Theexergydestructionsintheheatexchanger(condenserandevaporator),groundheatexchanger,pump,expansionvalve,andsolar collector are calculated as follows, respectively:C15 Heat exchanger:˙Exdest。 ˙mc (18)For exergy destruction (or irreversibility), the entropygeneration˙Sgenis calculated first and used in the followingequation:˙I 188。X˙mincinC0X˙moutcout188。out188。˙Exmass。ToutC0 Tin222。 ˙mwaCp。˙Wpumps254。˙Qcond˙Wp(10)The coefficient of performance of the overall heatingsystem (COPsys), which is the ratio of the condenser loadto total work consumptions of the pressor, the pumps(brine and water circulation pumps), and the fancoil unit (orthe condenser fan), may be puted by the followingequation:COPsys188。 (8)˙mair188。airC0 Tin。air240。p(7)In case that the mass flow rate on the refrigerant side isnot measured, the space heating load,˙Qsl, may be estimatedas:˙Qsl188。hi。˙mref240。h1C0 h4222。 (5)The heat transfer rate in the evaporator is:˙Qevap188。 ˙mref240。wa222。Tout。 ˙mwaCp。˙WoutC0˙Winis the rate of work output, and hthe specific enthalpy.Assuming no changes in kiic and potential energies withno heat or work transfers, the energy balance given in Eq. (2)can be simplified to flow enthalpies only:X˙minhin188。˙W。in188。X˙mouthout(2)where˙Q 188。X˙minhin188。˙Eout222。X˙mout(1)where ˙m is the mass flow rate, and the subscript ‘in’ stands forinlet and ‘out’ for outlet.The general energy balance can be expressed below as thetotalenergyinputequaltototalenergyoutput240。 received in revisedAbstractThis study deals with the energetic and exergetic modeling of groundperformance assessment. The analysis covers two various GSHPs, namelyofbothGSHPsystemsareevaluatedusingenergyandexergyanalysismethodalso presented in tables. Some thermodynamic parameters, such as fuelfactor, are investigated for both systems. The results obtained are discussedvaluation of ground sourcepump systemsHepbaslib,*, 35100 Bornova, Izmir, Turkey, Faculty of Engineering,Izmir, Turkeyform 23 April 2020。 Ground source heat pump。 Exergy analysis。 Energy。e, ArifBornova,depletionranged from to , while those for COPsysvaried between and . The exergy efficiency peak values for both whole systems on aA GSHP utilizes the ground as a heat source in heating and aloop GSHP system consists of a system of long plastic pipesEnergy and Buildings 39 (2020)buried vertically or horizontally in the ground [1–4].In a prehensive study performed by Lund et al. [5],itisreported that GSHPs have the largest energy use and installedcapacity according to the 2020 data, accounting for % and* Corresponding author. Tel.: +90 232 343 4000x5124。fax: +90 232 388 8562.Email addresses: (O. Ozgener), (A. Hepbasli).03787788/$ – see front matter 2020 Elsevier . All rights reserved.doi:borehole configuration is usually preferred over horizontaltrench systems because less ground areas are required. Thevertical ground heat exchanger consists of a number ofboreholes, each containing a Utube pipe. The depth of theborehole ranges usually between 40 and 150 m, and thediameter – m. The borehole annulus should begrouted with materials that provide thermal contact betweenthe pipe and the surrounding soil/rock and to protectgroundwater from possible contamination. The efficiency ofhouse or building. In the cooling mode, heat is absorbed fromthe conditioned space and transferred to the earth through itsground heat exchanger. GSHPs are an efficient alternative toconventional methods of conditioning homes because theyutilize the ground as an energy source or sink instead of usingthe ambient air. The ground is a thermally more stable heatexchange medium than air, essentially unlimited and alwaysavailable. The GSHPs exchange heat with the ground, andma